Tractor-drawn plow with hitch and furrow wheel hydraulic motors connected in series

ABSTRACT

A tractor-drawn plow is carried at its left front end on a tractor via vertically shiftable hitch means and at its right front end on a furrow wheel linkage means providing for raising and lowering of the frame among transport, open-up plowing and normal plowing positions. The hitch means and furrow wheel linkage include separate hydraulic motors of the two-way type, and these are connected hydraulically in series, with provision for re-phasing, to insure substantial leveling of the frame during raising and lowering movement of the frame. Provision is made in the connection of the hitch motor to the hitch means for enabling limited retrograde movement of the hitch motor piston to a position covering the re-phase port after the hitch motor has extended to fully raise the frame. Further provision is made in the furrow wheel linkage enabling lowering of the frame to either open-up plowing position or normal plowing position by retraction strokes of the same length of the furrow wheel motor.

BACKGROUND OF THE INVENTION

It is typical of the usual tractor-drawn plow that it is connected orsupported at its laterally spaced front portions by vertically shiftablehitch means on a tractor and on vertically shiftable linkage means on afurrow wheel. U.S. Pat. No. 3,236,313 discloses an arrangement in whichthe furrow wheel linkage includes a two-way hydraulic motor and thelinkage is mechanically connected to the hitch means so that operationof the motor activates the furrow wheel linkage and hitch meanssubstantially in unison so that substantial leveling of the plow frameis achieved during movement between raised and lowered positions. It isalso typical of such plow that, during lowering of the frame from fullyraised or transport position to a position for opening up the field, theframe will descend to a greater distance in relation to the front furrowwheel than when it is lowered from transport to the normal plowingposition, because, in the opening-up plowing position, the furrow wheelis traveling on unplowed land and, in normal position, the furrow wheelruns in a previously formed furrow. In the recent past it has beennecessary to control a hydraulic cylinder in two phases, one stroke forlowering to open-up plowing position and a different stroke for loweringto normal plowing position.

BRIEF DESCRIPTION OF THE INVENTION

It is a feature of the invention to provide mechanism for eliminatingthe deficiencies in prior art systems, especially with respect to thehitch leveling means and to the furrow wheel linkage. As to the hitchmeans, a system is provided for obtaining a substantial mechanicaladvantage so that raising and lowering is facilitated. As to the furrowwheel linkage, there is provided an automatically operativebi-positional mechanism enabling lowering of the plow to either of itsopen-up plowing or normal plowing positions by a hydraulic motorutilizing strokes of the same length in both phases of position change.The hitch means is provided with a two-way hydraulic motor or cylinderand piston unit and the furrow wheel linkage includes a separate two-wayhydraulic motor. These are hydraulically interconnected in series, withprovision for re-phasing of the respective pistons.

In the re-phasing aspect, the hitch piston, when fully extended to raisethe hitch means, uncovers a re-phasing port, which, if left uncoveredwhile an extension force is present, will prevent retraction of themotor for lowering operation. It is a feature of the invention toprovide means enabling the hitch piston to incur a limited amount ofretrograde movement sufficient to re-cover the re-phasing port. As willbe seen from the ensuing description, this means includes a slotted armhaving a pin riding in the slot and connected to the hitch piston rod,together with a stop which limits rocking of the arm in thehitch-raising direction so that the pin can ride in the slot to asufficient extent to achieve the aforesaid retrograde movement of thehitch piston.

The bi-positionable mechanism for the furrow wheel linkage takes theform of an arm rockable between two positions respectively at oppositesides of an over-center position, together with front and rear limitingstop means controlling rocking of the arm so that when it swings to oneposition it compensates for the difference in vertical travel of theplow frame as between open-up plowing and normal plowing positions, thusenabling the furrow wheel motor to have the same stroke in either case.

These and other features and advantages of the invention will be madeapparent as a preferred embodiment of the invention is brought out indetail in the ensuing description and accompanying sheets of drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a representative plow in which the inventionfinds utility.

FIG. 2 is a fragmentary plan view, drawn to a scale enlarged over thatused in FIG. 1, showing the hitch means and hitch motor.

FIG. 3 is a side elevation of the structure shown in FIG. 2.

FIG. 4 is an enlarged, fragmentary perspective showing the furrow wheellinkage and associated motor.

FIG. 5 is a side view, similar to FIG. 3 but enlarged, showing the hitchmeans as disposed in lowered position of the plow frame.

FIG. 6 is a similar view but showing the hitch as positioned when theplow frame is raised.

FIG. 7 is an enlarged section, with intermediate portions omitted, ofthe hitch motor and showing the hitch piston at the end of its extensionstroke.

FIG. 7A is a plan as seen on the line 7A-7A of FIG. 7 and showing therelationship of the main and re-phasing ports.

FIG. 8 is a schematic illustration of a representative form of hydrauliccircuit employed to connect the hitch and furrow wheel motors inre-phased series.

FIG. 9 is a schematic view on a reduced scale showing the relationshipbetween the plow frame and furrow wheel in fully raised or transportposition.

FIG. 10 is a like view but showing the parts in open-up plowingposition.

FIG. 11 is likewise a similar view but showing the parts in the normalplowing position.

FIG. 12 is a schematic view, on a scale enlarged over that used in FIG.9, showing the furrow wheel motor and over-center device as disposed inthe transport position of the plow.

FIG. 13 is similar to FIG. 12 but shows the parts in open-up plowingposition of the plow.

FIG. 14 follows the pattern of FIGS. 12 and 13 but shows the parts asthey are in the normal plowing position of the plow.

DETAILED DESCRIPTION OF THE INVENTION

Reference will be had first to FIG. 1 as setting the basis for theapplication of the invention. For purposes of illustration, a tandemplow is shown as having front and rear main frames or beams 20 and 22respectively. These are hinged together on a substantially transverseaxis in the area of the numeral 24. The front frame includes a series oftypical plow bottoms 26, some of which are omitted for clarity, and therear frame likewise has a series of bottoms 28. The front frame or beamincludes a forwardly extending hitch bar 30 which is rigid with theframe, at least as against relative vertical movement, and which issupported on hitch means 32 that includes a rigid hitch member 34connected to and supported by an angricultural tractor 36 having adrawbar 38. Since the frame 20 extends obliquely to the line of travel,its forward right end 40 is rightwardly of the left front end asrepresented by the hitch bar, and this right end is carried on a rightfront furrow wheel 42 by furrow wheel linkage 44 to be described later.The rear end of the frame 20, as well as the front end of the rear frame22, is supported by an intermediate wheeled support in the form of arubber-tired bogie 46, and the rear end of the rear frame is carried, asis typical, on a rear furrow wheel 48 and a gauge wheel 50.

As best seen in FIGS. 2 and 3, the front end of the rigid member 34 ofthe hitch means 32 derives support from the tractor drawbar via a clevis52 which includes a pivot 54 on a transverse axis and a vertical pivot56. The hitch bar 30 and the rigid member 34 are hinged together on atransverse axis or pivot 58, and the front left end of the frame 20 israised and lowered about the pivot 58 as the hitch bar and rigid member"buckle" upwardly or downwardly, thus giving the hitch means thecharacteristic of being vertically shiftable. Raising and lowering aboutthe pivot 58 is achieved by force-exerting means, here in the form of atwo-way hydraulic motor or cylinder and piston unit 60. Any suitabletype motor may be used for this purpose, that selected for illustrationbeing of the type known in the art as a remote cylinder. In the presentcase, reference will be had to the functions of this motor as raisingthe hitch means upon extension and lowering of the hitch means byretraction. It will be obvious of course that the parts could bereversed or connected with suitable linkage to accomplish the reversalof these functions. Hence, the description should be taken asillustrative or representative and not limiting.

The motor 60 includes a cylinder 62, a piston 64 (FIG. 7) and a pistonrod 66. The cylinder has an anchor 68 to the hitch bar 30 to the rear ofthe cross pivot 58, and the piston rod extends forwardly for connectionby force-transmitting means 70 to the hitch means rigid member 34. Forthis purpose, the hitch bar carries rigidly thereon and just to the rearof the pivot 58 an upstanding support 74, which may be of any suitabledesign, such as utilizing a pair of vertical plates between which an arm78 is rockable fore and aft by means of a pivot 76. The arm depends fromthe pivot 76 and has its lower end portion connected to the free end ofthe piston rod 66 by means 80, to be described in detail subsequently. Asecond upstanding support 82 is rigidly carried by the hitch means rigidmember 34 ahead of the pivot 58, and this support is operativelyconnected to the arm 78 by a force-transmitting connection such as alink 84. The front and rear ends of this link are threadably connectedat 86 and 88 respectively to the front support and arm 78, the rearconnection 88 being made to the arm below the arm pivot 76 so as toprovide the desired mechanical advantage as the motor 60 is extended andretracted. The threaded connections at 86 and 88 provide for variationsin the distance between the arm and the front support, which isaccomplished by means of a nut or like portion 90 rigid on theintermediate portion of the link. Extension of the piston rod 66 swingsthe arm 78 forwardly to exert a forward force on the front support 82,which causes the hitch bar and hitch means to pivot upwardly at thepivot 58, the hitch means rigid member 34 of course pivoting also aboutits pivot 54 to the tractor. Conversely, retraction of the motor 60causes lowering of the bar and member 30 and 34. FIGS. 3 and 5 show theparts in plowing or lowered position. FIG. 6 shows the parts in raisedposition. For the present, description of the hydraulic operation of themotor 60 will be deferred.

As previously described herein, the right front end of the plow frame 20is supported on the front furrow wheel 42 by means of the linkage 44.FIGS. 4 and 9 through 14 best show the details of the furrowwheel-to-frame support and raising and lowering of the frame relative tothe furrow wheel.

The furrow wheel includes an axle (not shown) which is integral or rigidwith an upstanding spindle 92 which is journaled on a vertical axis in acasting or carrier 94. The front end of the frame 20 has rigid thereon abracket or support 96, and the furrow wheel linkage 44 is here shown ascomprising a pair of parallel links 98 connected at opposite endsrespectively to the furrow wheel carrier and the main frame bracket 96.A second two-way hydraulic motor or cylinder and piston unit 100 isconnected between the furrow wheel carrier and the main frame bracket 96to achieve, in combination with the parallel links, raising and loweringof the frame. This, as will appear later, is coordinated with raisingand lowering of the frame by the hitch motor 60.

The furrow wheel motor includes a cylinder 102, piston 104 (FIG. 8) andpiston rod 106. The closed end of the cylinder has a pivotal connection108 with the furrow wheel carrier 94, and the piston rod extendsupwardly and rearwardly to connecting means 110 with the main framebracket 96. This means, as previously referred to, operates to enablethe same length extension stroke of the furrow wheel motor whether theplow is being lowered to normal plowing position or to open-up plowingposition. In the present instance, the motor 100 extends to raise theframe and retracts to effect lowering thereof. What has been said,however, concerning the reversal or parts, etc., as to the hitch motor60, applies equally well here.

The means by which the above results are obtained comprises abi-positionable mechanism incorporating an over-center device, whichhere includes an arm 112 rockable on the main frame bracket 96 about atransverse pivot 114. For the purposes of convenience and clarity therocking of the arm will be considered fore and aft, but here, as well asin the appended claims, such terms should be understood as relative andnot limiting.

The arm extends essentially downwardly and has its free end connected tothe end of the piston rod 106 by a transverse pivot pin 116 so thatextension and retraction of the furrow wheel motor rocks the arm. Therocking of the arm is controlled or limited to angular movement betweentwo positions respectively at opposite sides of a straight line drawnbetween the cylinder anchor pin 108 and the arm pivot 114. Controlledmovement of the arm in these two phases is accomplished by the provisionof front and rear stop means 118 and 120 respectively. These areprovided on the arm and are respectively engageable with front and rearportions or lugs 122 and 124 on the main frame bracket 96 (FIG. 12).FIGS. 9 and 12 show the components as disposed in the transport or fullyraised position of the plow. The furrow wheel motor is extended and thearm has been rocked forwardly to a position in which the rear stop meansis engaged, which prevents further counter-clockwise movement of the armand a pin 126 may be inserted through alined openings (not numbered) inthe arm and main frame bracket to retain this position. When not in use,the pin may be stored in a lower hole 128 in the bracket.

When the plow is to be lowered to normal plowing position (FIGS. 11 and14), and assuming that the furrow wheel 42 will track in a furrow, thepin 126 is left in place and the motor 100 retracted. If, however, afurrow is not present, as would be the case in opening up the land, thepin is removed and the motor is retracted. Because the plow will have todescend a greater distance in relation to the furrow wheel than whenlowered to a depth where a furrow is not present, the arm will snapover-center until the stops 118-122 engage (FIG. 13). This is becausethe furrow wheel, riding the land, is higher than when tracking in afurrow. Conversely, when it is desired to place the arm 112 back inposition for normal plowing, the plow is lowered to the ground until thefurrow wheel motor will involve over-center rocking of the arm until therear stops 12-124 engage, after which the locking pin 126 is placed inthe upper holes in the arm and main frame bracket or casting.

The operation of the over-center means may be better understood byconsidering lowering of the plow from FIG. 12 to FIG. 13. First the pin126 is removed and stored in the hole 128. As the furrow wheel cylinderretracts, pivoting of the furrow wheel is essentially about the pin 114until the line through 108-116-114 is reached, which is dead center. Asrelative movement between the plow frame and furrow wheel continues, thearm 112 snaps over-center in a clockwise direction. To return to theraised position from the open-up plowing position, the arm remains inthe aforesaid position. In any event, the raised position of the plow isat a constant height regardless of whether it is raised from open-upplowing position or from normal plowing position. The over-center meansprovides, however, for two furrow wheel plowing positions.

To change from open-up raised position to normal plowing position, theplow is drawn into position and the furrow wheel enters the furrow, theplow bottoms are still on land (unplowed) and the furrow wheel literallyhangs in the air. At this time, the tractor is stopped and the furrowwheel motor is retracted, lowering the plow bottoms to the ground;further retracting of the motor starts to raise the wheel from thefurrow bottom, thus rotating the arm 112 counter-clockwise until thestops 120-124 engage (FIG. 14). The pin 126 is replaced in the upperhole to retain this position for normal plowing position. When thetractor is driven forwardly, the bottoms enter the ground and the furrowwheel now runs in the furrow.

Reference has been previously made to that feature of the invention thatinvolves hydraulically connecting the hitch and furrow wheel motors inseries. Furthermore, the series connection includes provision forre-phasing of the pistons. In this respect, the description will proceedwith the hitch and furrow wheel motors. Although FIG. 1 shows hydrauliccontrol means for the bogie and rear furrow and land wheels, this aspectis not significant in the present case and will not be further advertedto. Also, for the purposes of simplicity and clarity, the lines orconduits pertaining to the hitch and furrow wheel motors have beenomitted in FIG. 1. Further reference will be had primarily to FIGS. 7,7A and 8 for the basic hydraulic circuit.

As indicated in FIG. 8, the tractor, as is typical, includes a hydraulicsystem comprising a pump P, a control valve V and a sump S. In oneactive position of the valve, a conduit 130 leads to the closed end ofthe hitch motor 60. A series conduit 132 leads from the rod end of themotor 60 to the closed end of the furrow wheel motor 100 and a returnconduit runs from the rod end of the furrow wheel motor back to thevalve and hence to sump. In the other active position of the valve, theconduits serve the reverse purpose. That is, the valve may beselectively positioned to pressure either motor.

In order that the series-connected motors may function accurately andefficiently, the hydraulic system includes means for re-phasing of thepistons. FIG. 7 shows a representative re-phasing means for the rod endof the hitch motor as comprising a main port 136 and a re-phasing port138. See also FIG. 7A. Assuming that the closed end of the hitch motoris pressurized, the main port is downstream of the re-phasing port. Asthe piston reaches the end of its extension stroke, it uncovers there-phasing port 138, enabling further pressurizing of the closed end ofthe furrow wheel motor 100 in the event that the piston therein is outof phase. The retraction stoke of the furrow wheel motor causesretraction of the hitch motor. The furrow wheel motor has main andre-phasing ports at 140 and 142 respectively.

As noted above and as shown in FIG. 7, the piston has reached the end ofits extension stroke. When fluid pressure is applied to the rod end ofthe hitch motor to cause retraction thereof, a pressure differential iscreated by the re-phasing port 138 across the piston 64. Therefore, ifthis pressure differential creates an inward force on the piston 64 lessthan the external extension force on the piston rod 66, the fluid willescape through the re-phasing port and the piston 64 will not retract.This problem is solved by the provision of means to remove the extensionforce on the piston rod 66. This means is best shown in FIGS. 5 and 6.

Reference was had earlier herein to the means 80 that connects thepiston rod 66 and the force-transmitting arm 78 of the hitch raising andlowering means 70. Part of this connection is a slot 150 in a lowerportion of the arm. Another portion is a cross pin 152 that passesthrough the free end of the piston rod and that rides in the slot. Asshown in FIG. 5, which is the lowered position of the plow, the slot,when the arm is in its rear position, is vertical or substantially so;i.e., it is normal to the general line of travel of the piston rod 66.This eliminates lost motion when the piston rod extends. A lower frontportion of the arm has an angled portion 154 which, after rockingforwardly of the arm to the position of FIG. 6, engages stop means 156on the support 76. It is at the end of this range of angular movement ofthe arm 78 that the hitch motor reaches the end of its extension stroke,which would mean that the hitch piston 64 uncovers the re-phasing port138 (FIG. 7), giving rise to the problem mentioned earlier; i.e., thepiston could not retract as long as there is an extension force on thepiston rod 66. But, when the arm engages the stop 156, the pin 152 ridesfreely in about the midportion of the slot, which in the position ofFIG. 6 inclines upwardly and rearwardly, thus removing any extensionforce on the pin 152 and rod 66. When the valve V is operated to causelowering of the plow, the differential pressure, as explained earlier,causes the piston 64 to retract, the pin 152 thus retracting freely inthe slot to allow the piston 64 to cover the re-phasing port 138 so thatthe main port 136 is fully open to the front face of the piston 64. Atthis point, it is important to note that, when the plow is in fullyraised position, the weight thereof is borne primarily on the frontfurrow wheel, the bogie and the rear wheels, the weight being generallyconcentrated along the line of the front and rear beams, thus removingsubstantially all of the plow weight from the hitch, meaning that thehitch can buckle upwardly. The reverse is the case to some extent whenplowing; i.e., the weight is more on the hitch.

It is believed that operation of the means comprising the invention willhave been made clear from the foregoing description. It will be seenthat operation of the hitch and furrow wheel motors substantially inunison results in leveling of the front ends of the plow during raisingand lowering. The incorporation of the furrow wheel control means,especially with reference to the over-center device including the arm112, supplies the necessary compensation for differences in functions asbetween lowering to plowing position when a furrow is present andlowering to plowing position when the furrow wheel must travel on land,as when opening-up the field, because in either case the retractionstroke of the furrow wheel motor is the same and operation of the valveV is facilitated.

It will be understood that what has been disclosed herein is based on apreferred embodiment of the invention, and, further, that language hasbeen employed in the description and claims such as will facilitate aready understanding of the invention; for example, the use of such termsas "right," "left," "extension," "retraction," etc., which are all termsof reference and not intended as limitations. Moreover, features andadvantages not readily apparent from the disclosure will make themselvesknown to those versed in the art, as will many modifications andvariations in the preferred embodiment disclosed, all of which may beresorted to without departure from the spirit and scope of theinvention.

We claim:
 1. In a tractor-drawn plow having a main frame disposedobliquely to the line of travel, a forwardly extending hitch bar rigidlyconnected to the left front end of the frame, vertically shiftable hitchmeans connected to the hitch bar and adapted to be supported on atractor, a front furrow wheel including a support member disposedadjacent to the right front end of the frame, linkage means connectedbetween the right front end of the frame and the furrow wheel supportmember for selective raising and lowering of the right front endrelative to the furrow wheel, the improvement residing in mechanism foroperating the hitch means and linkage means substantially in unison tomaintain the frame front ends substantially level during raising andlowering, said mechanism comprising: a two-way hydraulic furrow wheelmotor having a cylinder, piston and piston rod, means connecting thecylinder to the furrow wheel carrier, means connecting the piston rod tothe main frame right front end for operation of the motor upon extensionand retracting strokes respectively to raise and lower said right frontend, a two-way hydraulic hitch motor having a cylinder, piston andpiston rod, means connecting the hitch cylinder to the hitch bar, meansconnecting the hitch piston rod to the hitch means for operation uponextension and retracting strokes respectively to raise and lower themain frame left front end, hydraulic means interconnecting the cylindersfor operation in series, said hydraulic means including a re-phasingport upstream of the main port as the hitch piston rod extends so that,as the hitch piston reaches the end of its extension stroke, it firstcovers and then uncovers the re-phasing port, said connection of thehitch piston rod to the hitch means including means external to thehitch motor cylinder for effecting limited return of the hitch piston onits retracting stroke sufficiently to re-cover the re-phasing port. 2.The improvement according to claim 1, in which the connection of thehitch piston rod to the hitch means comprises a support on the hitchbar, a second support on the hitch means, an arm swingable on the firstsupport, a link interconnecting the arm and the second support, aconnection between the arm and the hitch piston rod including a slot anda pin fixed to the hitch piston rod and riding in the slot, a stop onthe first support for engaging the arm upon swinging thereof to the endof the extension stroke of the hitch piston, said slot enabling limitedretrograde movement of the pin in the direction of retraction of thehitch piston sufficiently to enable the hitch piston to recover there-phasing port.
 3. The improvement according to claim 2, in which thelink is adjustable to provide for variations in the distance between thearm and the second support.
 4. The improvement according to claim 1, inwhich the hitch means includes a rigid member having a front endprovided with a transverse pivot for support on the tractor and a rearend provided with a transverse pivot connected to the hitch bar, and thehitch motor has its cylinder connected to the hitch bar rearwardly ofthe rear pivot and further has its piston rod connected to the rigidmember ahead of said rear pivot for raising the hitch bar and rigidmember at the rear pivot upon extension of said motor and for loweringthe hitch bar and the rigid member at said rear pivot upon retraction ofsaid motor.
 5. The improvement according to claim 4, in which the rigidmember has rigidly thereon a front upstanding support disposed ahead ofthe rear pivot, the hitch cylinder has an anchor to the hitch barrearwardly of said rear pivot and the hitch piston rod has aforce-transmitting connection to the front support for swinging therigid member forwardly and upon extension and retraction, respectively,of the hitch motor. PG,16
 6. The improvement according to claim 5, inwhich the hitch bar has rigid thereon a rear upstanding support disposedto the rear of the rear pivot and ahead of the hitch cylinder anchor,and the force-transmitting connection includes an arm pivoted at itsupper end to the rear support on a transverse pivot and a link connectedbetween an intermediate portion of the arm and the front support,whereby extension of the hitch motor swings the arm forwardly to exert aforward and downward force on the front support via the link andretraction of the hitch motor swings the arm rearwardly to exert arearward and upward force on the front support.
 7. The improvementaccording to claim 6, in which the rear support has a stop thereonengageable with the arm upon predetermined forward swinging thereof, andthe connection of the hitch piston rod to the arm includes a rearwardlyand upwardly inclined slot in the arm and a pin on the hitch piston rodengages in the slot, said slot providing for rearwardly movement of thepin when the arm is engaged with the stop.
 8. The improvement accordingto claim 1, in which the means connecting the furrow wheel piston rod tothe main frame includes bi-positionable mechanism accommodating thedifference in vertical distances between the main frame and furrow wheelin open-up plowing and normal plowing positions and thereby providingfor retraction strokes of the furrow wheel motor of the same length inlowering the main frame to either of said positions, said mechanismincluding an over-center device automatically shiftable to one side of acenter position when the main frame is lowered to its open-up plowingposition and to the opposite side of said center position when the mainframe is lowered to its normal plowing position.